Compare the values of the two quantities in the question and answer. Quantity 1: A bag contains 20 balls which are red, green and blue. Find the number of red balls in the bag, if the probability of picking a blue ball is 2/5 and that of either a red or a blue ball is 3/4. Quantity 2: A bag contains 25 balls which are red, green and blue. The probability of picking a red ball first is 2/5. If the first ball was red and without keeping it back, probability of picking a blue ball is 1/3, find the number of green balls.?

Option 5 : Quantity 1 = Quantity 2

Solving for Quantity 1:

Probability of picking a blue ball = no. of blue balls/20 = 2/5

⇒ No. of blue balls = 40/5 = 8

Probability of picking either a red or blue ball = (no. of red balls + no. of blue balls) /20 = ¾

⇒ No. of red balls + no. of blue balls = 15

⇒ No. of red balls = 15 – 8 = 7

⇒ Quantity 1 = 7

Solving for Quantity 2:

Probability of picking a red ball first = no. of red balls/25 = 2/5

⇒ No. of red balls = 10

Probability of picking a blue ball without keeping the first ball back = no. of blue balls/24 = 1/3

⇒ No. of blue balls = 8

⇒ No. of green balls = 25 – (10 + 8) = 25 – 18 = 7

⇒ Quantity 2 = 7